Radio Frequency Identification (RFID) systems are used for many varied applications. RFID tags can be used as security devices for prevention of theft of articles, for personnel identification, for building security applications, and for animal tagging. An RFID tag can be used to identify any physical article, be it product, animal, or person, in these applications. Interacting with the RFID tag is an RFID reader which includes an antenna to read tags, thus identifying the object.
When using an RFID antenna outdoors, for animal management purposes or for identifying products or people, the antenna is subject to external forces which may degrade or break the antenna. The antenna may also oxidise due to the weather causing water to seep into the antenna housing, or other caustic substances affecting the antenna's performance.
The geometry of the antenna used to read RFID tags is important, as the shape of the antenna defines the area in which it can read tags. The antenna usually is formed in a closed curve, which maximises the spatial volume in which a tag can be read. The housing that the antenna is in must hold the antenna in this shape, as well as protecting the antenna from outside forces.
Current housings for antennas used in RFID systems are usually made from a plastic material housing, which is injection moulded in two or more parts. These parts are joined together at a seam interface which offers a way for water to enter and potentially oxidise the antenna.
Injection moulding also has a high tooling cost, and generally forms only solid parts. Other techniques such as thermoforming and spray coating can be used, but these methods also result in a housing which is moulded in two or more parts.
Rotational moulding, in which plastic particulate material is rotated and heated to create hollow parts, is another alternative for creating plastic components. This process is usually used to create medium to large hollow items. However, this method makes no allowance for an antenna to be placed inside the finished article without an entry hole being created after the moulding step. This hole, when stopped, would again suffer from problems with the join creating a weak point in the housing.
It would be preferable to have a one piece housing for an antenna which is solid, resistant to external forces or impacts, and also resistant to water or other corrosive substances.
It would also be preferable to have a method of manufacturing a housing which fits these requirements, and is also fast and relatively simple to execute. Furthermore, it would be preferable to have a method of rotationally moulding a single integral housing which encloses and locates an internal element.
All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.
It is acknowledged that the term ‘comprise’ may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, the term ‘comprise’ shall have an inclusive meaning—i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements. This rationale will also be used when the term ‘comprised’ or ‘comprising’ is used in relation to one or more steps in a method or process.
It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.
Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.